1. Field of the Invention
The present disclosure relates to devices for controlling electrical power to loads, and power supplies for such devices.
2. Description of Related Art
The most conventional switch for controlling the operation of a remote load is a toggle switch that requires no control power to operate. An example of such a conventional switch is the common wall-mounted light switch. In existing construction utilizing such conventional switches, a neutral conductor from an alternating current (AC) source (e.g., from a circuit breaker panelboard) is oftentimes run to the load but not to the switch. An energized line conductor (also called a “hot” conductor, or a “phase” conductor, or simply a “line” conductor) is run from the AC source to the switch, along with a grounding conductor to ground the switch, its enclosure, conduits, etc. A load conductor is run from the switch to the load, to supply power to the load from the AC source when the switch is closed.
Some advanced electronic switches, such as certain dimmer switches, require control power. Such advanced electronic switches can be intended to replace existing conventional switches in retrofit applications. Since conventional switches may only have a line conductor, a load conductor and a grounding conductor available locally at the switch, it would be desirable for advanced electronic switches to be able to derive control power from only the available wiring (e.g., without requiring a neutral conductor to be run to the switch). If current is to be conducted to earth ground by such a switch, and an applicable industry or governing standard defines a maximum amount of current that is permitted to be conducted to earth ground, then it would be desirable to limit the current conducted to earth ground to such a level.